Method and apparatus for forming yarn

ABSTRACT

In a spinning operation in which two strands are fed from separate nip positions and are twisted together into a single ply at a convergence point, twist is incorporated into the single strands by cyclically varying the path lengths of the strands between the nip positions and the convergence point. Preferential spiralling of one strand about the other is prevented by ensuring that the ratio of feed of the strands to the convergence point are substantially equal.

Un ted States Patent [151 3,695,019 Lappage [451 Oct. 3, 1972 [54] METHOD AND APPARATUS FOR 3,199,283 8/1965 Livingston ..57/91 X FORMING YARN 3,113,413 12/1963 Jacobs et a1. ..57/91 X 2,731,789 1/1956 Holden-.4. ..57/91 X [72] 'f f g? 3,443,370 5/1969' Walls ..57/77.3 x 6 3,377,792 4/1968 Walls et a1. 57177.3 [22] Filed: June 16, 1970 2,981,047 4/1961 Jansen ..57/ 106 X 2,961,010 11/1960 Berry ..57/139 X [21] 46,666 3,306,023 2/1967 Henshaw et al.; ..57/34 A T [30] Foreign Ap li ti P i it D t Primary ExaminerDonald E. Watkins June 17 1969 Australia 56569/69 Att0rney-Sughrue, Rothwell, Mion, Zinn & Macpeak 57 ABSTRACT [52] U.S.= Cl. ..57/38.3, 57/139, 57/156 1 [51] Int. Cl "D0", 7/00, oz 3/26, oz 3/28 In a spmnlng operation in which two strands are fed 58 Field Of Search ..57/34,36, 12 38.3, 58.52, fmm Separate P and are twisted wgether 57/91 139 140 into a single ply at a convergence point, twist is incorporated into the single strands by cyclically varying [56] References Cited the path lengths of the strands between the nip positions and the convergence point. Preferential UNITED STATES PATENTS spiralling of one strand about the other is prevented 3 2 5 5 1 9 H h 57/34 by ensuring that the ratio of feed of the strands to the 3 3 595 /196 ZS S: I convergence point are substantially equal. 1,916,377 7/1933 Kreis ..57/9l X 9 Claims, 9 Drawing Figures PATENTEDucrs m2 SHEET 2 [IF 4 METHOD AND APPARATUS FOR FORMING YARN BACKGROUND OF THE INVENTION This invention relates to the production of textile yarns and in particular, although not exclusively, the production of yarns from staple fibers such as wool fibers, wherein the fibers are aligned to form rovings and the rovings are thereafter attenuated and twisted to form a yarn. The yarns used, particularly in weaving, are often what are known as twofold yarns," i.e., they comprise two separate single yarn ends which are plied together to form the twofold yarn. The objective in using twofold yarns rather than singles yarns is to improve the performance of the yarns in subsequent process such as weaving, and to enhance the properties of the resulting fabrics.

PRIOR ART The conversion of textile roving into twofold yarns is, by the conventional methods, a fairly long and costly part of textile processing. Firstly singles yarns are spun to a desired count mass per unit length and with a desired amount of twist. Singles yarns are not as suitable for weaving as twofold yarns because they have a poor resistance to wear in the loom and, although this can be improved by using a sizing process, cloths into which singles yarns are woven may lack certain desirable qualities such as handle and drape. Often, therefore, two such singles yarns are twisted together such that a twofold yarn of suitable strength and resistance to wear is produced. Thus, according to the conventional process, there are involved two separate spinning type operations, one for each singles yarn, and a doubling operation to ply the two singles yarns together to form the twofold yarn.

In the ensuing discussion reference will be made to the twist in the strands and in the ply of a plied yarn. It is to be understood that the existence and direction of twist is relative to the viewing position of the observer. Throughout this specification and claims the twist will be described as it would be seen by a stationary observer from a position displaced laterally from the yarn.

It is well known to produce a singles yarn from two separate rovings fed side by side through the same drafting mechanism. Such yarns, sometimes called double-rove yarns are, however, quite different from twofold yarns in that there is theoretically no twist in the individual strands other than that which exists by virtue of the plying together of the two strands; i.e., there is substantially only the plying twist. There is therefore no twist in the strands tending to retain the separate identity of the strands and they tend to merge together. Such yarns do not therefore possess the required characteristics such as abrasion resistance and fabric handle and configuration obtained with twofold yarns. Another example of double-rove yarns may be seen in British Pat. specification No. 1,062,594 wherein the two rovings are fed separately to a convergence position.

As explained in British Pat. No. 1,062,594, during the spinning of a double-rove yarn, twist exists in each of the single strands between the point of convergence of the strands and the point where the strand is last gripped by the drafting mechanism, but this twist is not, in a theoretically perfect system, incorporated into the resultant yarn. This twist exists in the strands prior to convergence in an equilibrium quantity depending upon the geometry of the system and spinning parameters. lt is not incorporated in the structure of the double-rove yarn because, in equilibrium, it runs along each singles strand towards the drafting units with a speed equal and opposite to that with which the singles strands are spun.

The state of affairs described above is, in practice, modified by the fact that due to randomly occurring irregularities in the strands some of the twist is in fact incorporated into the strands in a randomly varying manner. Such twist is however of low intensity.

It is also known that if two or more travelling strands are being twisted together and if the distance travelled by one of the strands in passing from the nip position to the convergence point is cyclically varied then that strand can be caused to wrap around the other strand to produce a novelty or effect yarn. Examples of such yarns are shown in U.S. Pat. Nos. 3,019,593, 3,113, 413 and 3,412,543.

In U.S. Pat. No. 3,019,593 of R.T. Reid there is described a process in which three strands are twisted together and the path length of one of them is varied so as to provide yam storage when the path length is longest and to release the stored yarn when the path length is shortened. This produces yarns in which zones are created in which the said third yarn is alternatively heavily and lightly wrapped about the other two yarns.

U.S. Pat. No. 3,113,413 of H. Jacobs and A. More head describes a similar process in which there are twisted together two yarns which have their path lengths varied in opposite phase so that first one yarn is stored and then the other to provide a ply in which the one yarn wraps about the other and then the other wraps about the one. U.S. Pat. No. 3,412,543 of L. Horvath shows the application of this technique to the creation of slubs in false twisted multifilament singles yarns formed by the spindle-less method wherein the plys are first twisted and then separated.

SUMMARY OF THE INVENTION The yarns produced by the processes of the abovementioned U.S. specifications are novelty yarns and although the yarns may actually have some singles twist those processes can only be used to produce nonuniform weaving yarns for novelty or fancy fabrics. The yarns disclosed herein are intended for weaving into normal fabrics and are uniform in the sense that at any position along the length of the yarn the single strands are wound substantially equally about one another with neither predominating. We have now found that it is possible to twist together two or more strands in such a way that singles twist is incorporated equally into each of the strands to produce such uniform yarns (using the word uniform in the sense above defined).

This invention accordingly has as its principal object to produce, in a single twisting operation, a uniform yarn comprising at least two strands plied together, wherein there is twist in each of the individual strands and the strands are wound equally about one another.

In the process of our invention a uniform yarn is produced from at least two running strands in a single spinning operation. The process comprises the steps of separately feeding each strand from a feeding point to a convergence point, twisting the strands together at the convergence point and at the same time causing the distance between the convergence point and the feeding points of the strands to be cyclically varied. This causes additional singles twist of alternating direction to be trapped in the strands and incorporated into the structure. Preferential spiralling of one strand about the other is prevented according to this invention by ensuring that the rates of feeding each strand to the convergence point are substantially equal. It is generally convenient that the feeding points of the strands are arranged so that they are symmetrical about a plane passing through the convergence point and the convergence point is moved cyclically within that plane such that the angle subtended by each strand with the plane at the convergence point is cyclically varied.

The twist in the plied structure is unidirectional twist with cyclically recurring regions of high and low twist intensity. The twist in the strands, relative to the strand axis is cyclically reversed, i.e., these are cyclically recurring regions of S twist followed by regions of Z twist separated from the S twist by regions of no twist. The phase relationship between the twist in the strands and the twist in the plied structure is such that regions of like twist in the strands are in phase with one another, and the regions of high intensity twist in the plied structure coincide with regions in the strands where the twist direction is opposite, e.g., if the plying twist is say, S-twist, the regions of high intensity plying twist will correspond with regions of Z-twist in the individual strands.

An apparatus for producing the above described yarn comprises essentially, means to feed each strand from a feeding point to a convergence point, convergence means to converge the strands and twisting means to insert twist into the converged strands, and means for cyclically varying the distance between the convergence point and the feeding points of the strands while maintainingthe rates of feed of each of the strands to the convergence point substantially equal.

There are preferably at least two yarn feeding points disposed symmetrically about a plane passing between them, a convergence guide located in that plane, and

. means to move the convergence guide within the plane so that the angle subtended with the plane by lines joining the feed points to the convergence pointmay be cyclically varied. These requirements can be fulfilled by relatively simple modification of conventional spinning machinery.

Yarn according to this invention may be produced from for example, staple fiber rovings on conventional spinning machinery by providing a convergence guide to converge the strands from two separately drafted rovings at a point between the drafting mechanism and the spinning spindle and means whereby the convergence guide can be moved to vary the distance between it and the drafting mechanism.

The invention may be better understood by reference to the accompanying drawings in which there is shown, diagrammatically purely by way of example, a a

conventional spinning mechanism in which this is done.

FIG. 1 is a schematic view showing a spinning spindle fed froma pair of separate drafting mechanism and illustrating the principle of the invention.

FIG. 2 is a front elevation of an actual apparatus of the type indicated in FIG. 1.

FIG. 3 is a cross sectional view on the line 3-3 in FIG. 2.

FIG. 4 is a view on the line 4-4 in FIG. 2.

FIG. 5 is a perspective view of the suction tube shown in FIGS. 2 and 3.

FIG. 6 is a front elevation of an alternative apparatus in which both rovings are fed from separate feed points on the one drafting mechanism and in which an alternative means is provided for varying the position of the convergence point.

FIG. 7 is y a diagrammatic illustration of a yarn produced according to the invention.

FIG. 8 is a graph showing the twist distribution in the strands and in the ply of a yarn produced by the method of this invention and FIG. 9 is a graph showing the twist distribution in the strands and in the ply of a double-rove yarn produced by a process similar to that described in prior British Pat. specification No. 1,062,594.

DESCRIPTION OF PREFERRED EMBODIMENTS In the drawings the reference numeral 1 indicates the front drafting rollers of a pair of side by side conventional apron or like drafting mechanism. The reference numeral 2 indicates a balloon control guide which may be of the simple pot eye" type, and I3 is the spindle of a conventional ring spinning machine having a ring 4 and a traveller 5 by which yarn is twisted and wound onto the package 6 to form a yarn.

Strands 7, 8 are fed from the drafting rollers l to a centrally placed convergence guide 10 where they are converged to form a yarn 9 which is twisted by the combined action of the traveller 5 and the spindle 13.

The arrangement thus so far described is substantially similar to known prior art arrangements for the production of double-rove yarns shown in British Pat. specification No. 1,062,594 and if the convergence guide 2 is kept stationary in the position Y shown in the drawing, the yarn 9 would comprise two strands twisted together but with no individual twist within them other than the plying twist. During the spinning process twist would be developed in the strands 7 and 8 upstream from the convergence guide, but that twist, once the equilibrium state had been reached, would disappear at the convergence point and only plying twists would be present in the yarn.

According to this invention, however, the convergence guide is not left stationery at position Y but is rapidly moved up to the position X. When this is done, the point at which plying together of the yarns takes place, is likewise moved from Y to X so that over the distance YX the strands are plied together and at the same time some of the twist which existed in the separate strands over that distance is trapped in the strands. The convergence guide is now moved back to the position Y and twist builds up in the strand until the equilibrium condition is again reached. During this time strand twist of opposite direction is trapped in those parts of the strand entering the ply structure. The convergence guide is now again moved back to X trapping more twist, and so on. Thus there is produced, according to this invention, a yarn comprising two strands which are plied together and in which there is twist in each of the individual strands separately of the plying twist. We have found that the twist direction of the twist trapped in the individual strands reverses cyclically along the length of the strand. The plying twist on the other hand is unidirectional but the plying twist level will vary along the length of the strand and it will vary in such a way that the twist in the strands will be opposite to the plying twist at the points where the twist level in the ply is highest, and will be in the same direction as the plying twist where the twist level in the ply is lowest. There will thus be a substantially constant twist level throughout the yarn as a whole.

The actual manner in which the twist intensity varies throughout the structure can be adjusted by varying the motion of the convergence guide 10. The motion of this guide may, for example, be controlled by a cam which is designed, having regard to the forward feeding speed of the strands 7 and 8, to oscillate the convergence guide so that a twist variation is produced in which the twist half cycles are of equal lengths. It will be understood, however, that by suitably varying the motion of the convergence guide the manner of variation of the twist intensity in the strands 7 and 8 and the yarn 9 may likewise be varied.

It will be noted also that the drafting mechanisms are disposed symmetrically about a plane containing the line XY and that the angles subtended by each strand with that line are always equal. Since the delivery rates of the two drafting mechanism are equal the rates of feed of the two strands to the convergence point will be equal and likewise, at any given time, the tensions in the two strands will be equal. Because of this, if the weights of the two strands are substantially equal, the strands will wrap equally about one another to produce a uniform yarn, i.e., there will be no tendency for one yarn to form a larger helix than the other whereby it becomes a wrapping yarn and the other becomes a core as in the prior art novelty yarns referred to above.

FIG. 7 shows diagrammatically a yarn produced according to this invention and it will be seen that this yarn comprises a pair of strands 7, 8 plied together to form the yarn 9. It will also be seen that there are cyclically recurring zones A of relatively high intensity ply twist separated by zones B of relatively low intensity ply twist. It will also be observed that in the zones A where the twist intensity in the ply is high, the twist direction in the individual strands is opposite to that in the ply. Likewise it will be seen that in the zones B where the plying twist intensity is low, the strand twist is in the same direction as the plying twist.

The twist distribution in an actual yarn produced according to this invention is shown in FIG. 8. This figure shows the variations in twist in the ply and in the strands of a 70 tex yarn having a worsted twist factor of 3.3 wherein the convergence guide was moved according to this invention with a stroke of 9 cm. and the cycle length was cm (the worsted twist factor is a factor obtained by dividing the twist in turns per inch by the square root of the worsted count).

The upper curve C in FIG. 8 shows that the plying twist in the yarn varies about a mean of about 5 turns per cm in a roughly sinusoidal form with an amplitude of approximately 2% turns per cm. The lower curve D shows the twist distribution in one of the strands. In order to determine this twist distribution the ply was unwound by back twisting it approximately 5 turns per cm. It will be seen that the twist distribution in the strand (after back twisting) varies between approximately plus 0.7 and minus 0.7 and that the distribution curve is of substantially the same form as the curve C but is in opposite phase. The twist distribution in the other strand is not shown but it follows the curve D.

FIG. 9 shows the twist distribution in the ply and in the strand of a yarn of the same count and the same worsted twist factor as that of FIG. 8 but in this case the convergence guide in the apparatus was left in its lower-most position and the convergence point was allowed to locate freely. The method of production of the yarn was therefore substantially the same as that described in British Pat. No. 1,062,594. In the graph the upper curve E represents the twist distribution in the ply and it will be seen that this varies randomly about an average of approximately 5 turns per cm with a maximum of 5.75 turns per cm and a minimum of 4.5 turns per cm. The lower curve shows the twist distribution in the strand after back twisting about 5 turns per cm and this shows a random twist distribution varying between about plus and minus 0.3 turns per cm. It will also be seen that there are substantial lengths of the yarn in which the strand twist is substantially zero.

A practical apparatus for the production of the above described yarn is shown in FIGS. 2 to 5. This apparatus comprises essentially a conventional spinning frame having drafting mechanisms 11, 12 each arranged to deliver a strand to the traveller 5 of a spinning spindle 13. The spinning frame is however modified in that there is only one spindle located midway between each drafting mechanism. The frame is further modified in that there is provided a suction tube 14 mounted on a rocker shaft 15 which is driven by means of crank mechanism 16 which is oscillated by a cam 17 driven by chain 18 from a sprocket 19 on the end of the front drafting roller shaft 21. This causes the suction tube to oscillate between the positions shown in full lines and in dotted lines in FIG. 3.

The ends of the suction tubes 14 are connected by flexible tubes 22 to a suction manifold (not shown).

As shown in FIG. 5 the outer end of the suction tubes is slotted with slots 23 forming a fork in the tube equivalent to the fork 10 in the convergence guide shown schematically in FIG. 1. After convergence the plied strands 7 and 8 fed from the drafting mechanisms pass through this slot and as the tube is oscillated the convergence point of the strands is moved backwards and forwards in the manner above described.

Shields 24, 25 are provided to isolate each set of drafting mechanisms from one another and to render the operation of piecing up more simple in the event of a break in one of the strands. From this latter point of view the apparatus is substantially self-threading in that in the event of a break in one of. the strands the broken end is prevented from falling down by the plate 25 and is sucked into the suction tube wherein it is quickly caught up by the remaining rotating strand and piecing is thereby accomplished automatically.

In the embodiment of the invention described above by way of example, the yarn of this invention is produced merely by moving the convergence guide backwards and forwards along the line XY. It will be appreciated, however, that there are many other ways in which similar results may be produced. For example the effect may be produced by a pair of guides oscillating in a direction perpendicular to XY and in the plane of the singles strands such that two guides rapidly approach the point X in FIG. 1 from opposite sides, coming to rest momentarily a short distance apart on each side of the forming yarn and then quickly withdrawing. Such an apparatus is shown in FIG. 6.

in the apparatus of FIG. 6, two strands 7, 8 are fed simultaneously from each drafting mechanism and are led through pot eye 2 to the spindle as before. In this case however the control of convergence is effected by means of fingers 26, 26' attached to reciprocating rods 27, 28 driven by oscillating gear and pinion 29, 30. A suction tube 31 is again provided but in this case it remains stationary and merely performs the normal functions of the removal of fly and aiding in piecing as previously described.

Other modifications are also possible; the path lengths of the strands can for example be varied without altering the angle made by the strands at the convergence point.

The above description has been applied particularly to the production of a yarn which can be used in place of conventional twofold yarns. It is to be understood, however, that this new yarn and its method of production could be used in circumstances where singles yarns are now used. For example, cotton weaving yarns are often singles yarns which are sized before weaving. The

' yarn produced by this invention could be used in place of the singles yarn to give improved performance in the yarn in subsequent processing and to eliminate in some cases the necessity for sizing.

I claim:

1. A method for producing a uniform yarn from at least two running strands which comprises the steps of separately feeding each strand from a feeding point to a convergence point, maintaining the rates of feeding of each strand to the convergence point substantially equal, twisting the strands together at the convergence point and at the same time causing the path length between the convergence point and the feeding points of the strands to be cyclically varied.

2. A method as claimed in claim 1, wherein the feeding points of the strands are arranged so that they are symmetrical about a plane passing through the convergence point and the path lengths of each strand are varied equally and simultaneously.

3. A method as claimed in claim 2, wherein the convergence point is moved cyclically within the said plane such that the angle subtended by each strand with the plane at the convergence point is cyclically varied.

4. Apparatus for producing yarn from at least two strands comprising means to feed each strand from a feeding point to a convergence point, convergence means to converge the strands and twisting means to insert twist into the converged strands, and further comprising means for cyclically varying the path length between the convergence point and the feeding points of the strands while maintaining the rates of feed of the strands to the convergence point substantially equal.

5. Apparatus as claimed in claim 4, wherein there is provided means for feeding at least two yarns from feeding positions disposed symmetrically about a plane passin between them, a conver ence guide located in hat p ane, and means to vary t e pat lengths of the strands equally and simultaneously.

6. Apparatus as claimed in claim 5, wherein there is provided means to move the convergence guide within the plane so that the angle subtended with the plane by lines joining the feed points to the convergence point may be cyclically varied.

7. Apparatus as claimed in claim 4 further comprising a spinning frame having at least one drafting mechanism and a spinning spindle and means to draw at least two single rovings from the drafting mechanism through the convergence means to the spindle.

8. Apparatus as claimed in claim 7, wherein there are at least two drafting mechanisms and one roving is drawn from each.

9. Apparatus as claimed in claim 8, wherein each roving is delivered from the drafting mechanism at the same speed. 

1. A method for producing a uniform yarn from at least two running strands which comprises the steps of separately feeding each strand from a feeding point to a convergence point, maintaining the rates of feeding of each strand to the convergence point substantially equal, twisting the strands together at the convergence point and at the same time causing the path length between the convergence point and the feeding points of the strands to be cyclically variEd.
 2. A method as claimed in claim 1, wherein the feeding points of the strands are arranged so that they are symmetrical about a plane passing through the convergence point and the path lengths of each strand are varied equally and simultaneously.
 3. A method as claimed in claim 2, wherein the convergence point is moved cyclically within the said plane such that the angle subtended by each strand with the plane at the convergence point is cyclically varied.
 4. Apparatus for producing yarn from at least two strands comprising means to feed each strand from a feeding point to a convergence point, convergence means to converge the strands and twisting means to insert twist into the converged strands, and further comprising means for cyclically varying the path length between the convergence point and the feeding points of the strands while maintaining the rates of feed of the strands to the convergence point substantially equal.
 5. Apparatus as claimed in claim 4, wherein there is provided means for feeding at least two yarns from feeding positions disposed symmetrically about a plane passing between them, a convergence guide located in that plane, and means to vary the path lengths of the strands equally and simultaneously.
 6. Apparatus as claimed in claim 5, wherein there is provided means to move the convergence guide within the plane so that the angle subtended with the plane by lines joining the feed points to the convergence point may be cyclically varied.
 7. Apparatus as claimed in claim 4 further comprising a spinning frame having at least one drafting mechanism and a spinning spindle and means to draw at least two single rovings from the drafting mechanism through the convergence means to the spindle.
 8. Apparatus as claimed in claim 7, wherein there are at least two drafting mechanisms and one roving is drawn from each.
 9. Apparatus as claimed in claim 8, wherein each roving is delivered from the drafting mechanism at the same speed. 